Hydraulic cement mortar and method of compounding the same



I06. COMPOSITIONS,

COATING OR PLASTIC.

Patented May 9, 1933 UNITED STATES PATENT OFFICE FREDERICK C.LANGENBERG, OF EDGEWATER PARK, AND HORACE S. HUNT AND HERBERT G.REDDICK, 0F BURLINGTON, NEW JERSEY, ASSIGNORS TO UNITED STATES PIPE ANDFOUNDRY COMPANY, OF BURLINGTON, NEW JERSEY, A CORPORA- TION OF NEWJERSEY HYDRAULIC CEMENT MORTAR AND METHOD OF COMPOUNDING THE SAME NoDrawing. Original application filed July 29, 1931, Serial No. 553,895.Divided and this application filed January 26, 1932. Serial No. 589,040.

Our invention relates to an hydraulic cement mortar of an improvedquality and to the method of compounding such an improved mortar.

Hydraulic cement mortars and concretes as heretofore generallymanufactured are found to incorporate considerable percentages ofuncombined lime which is produced as a reaction. product in thehydration and setting of cement and may in some cases be present in thecement before hydration. This uncombined lime is quite freely soluble inwater and for this reason mortars embodying uncombined lime areundesirable as lining for pipes, tanks, or other containers designed asconduits or containers for water, and such mortars or concretes havealso objectionable qualities for other uses because the elimination oflime by solution tends to make the mortar or concrete porous and impairits strength, and also because the carbonic acid in the air has atendency to react with the lime, forming particles of carbonate of limeof larger size than the original particles of lime, the formation ofwhich in a set concrete has a more or less disruptive effect.

The object of our invention is to provide a method of compounding anhydraulic cement mortar or concrete in which the free lime particleseither present in the cement or produced as reaction products during thehydration and setting of the cement will be converted into practicallyinsoluble lime salts which will form an unobjectionable component of theset mortar, such enlargement of the particles as may be due to theconversion of the lime to an insoluble lime salt being entirelyunobjectionable because it occurs during the hydration and before thesetting of the cement and therefore has no disruptive tendency. We havefound that by mixing with the cement in the formation of a mortar asubstance containing monogalciun silicate. pggferablyaffi'ely groundblast furiiace slag, it is possibletodim'iiiisli tl'ie percentage offree lime in the resultant set mortar, the reaction being no doubtbetween the free lime incident to the hydration of the cement and themonocalcium silicate to form a dicalcium silicate uble acid non-reactivewith the aluminate and silicate components of the cement but reactivewith free lime to form an insoluble lime salt that here again it ispossible to effect a diminution in the percentage of free lime whichwould otherwise be present in the set mortar, but here again we havefound it impracticable by this expedient to form a mortar substantiallyfree from free lime. We have discovered however that by mixing in themortar both the finely ground blast furnace slag containing themonocalcium silicate and uncombined oxalic acid dissolved in the waterWife mpoi l h emortar, that we can and do produce a set mortar orconcrete in which substantially all of the free lime which wouldotherwise be incorporated in the mortar is converted into insoluble limesalts, with the result that a mortar or concrete is produced ofexceptionally fine texture and strength. embodying practically nosoluble elements and highly resistant to detrimental effects fromexposure to water or air. This mortar is particularly valuable as alining for water containers, such as pipes and tanks, owing to itsfreedom from soluble contaminating components and owing to its densityand lack of porosity, and when applied centrifugally, as in the liningof pipes, or properly trowelled on its surface, it is more easy toproduce on the surface a smooth, dense and repellant layer, which formsan additional protection against the permeation of the mortar by water.

Our invention consists in the described method of compounding such amortar or concrete and in the wet mortar mixture produced by this methodwhich in setting results in the production of a hydrated hy- 1 Examinedraulic cement mortar characterized in that its lime content issubstantially all present in the form of insoluble compounds partly ofinsoluble compounds of the calcium with silicon and aluminum and partlyin the in- SOllble compounds of the calcium with oxalic ac1 In practice,and for the best results, we compound our mortar by mixing with thehydraulic wapproximately 22 parts of finely ground b 100 parts ofcement, adding with and dissolved in the water approximately 1 percentof uncombined o: which acid is reactive with free lime to form aninsoluble lime salt and non-reactive with the aluminates and silicatesof the cement and of course aggregate materials suitable for makingmortar or concrete of any desired kind are also to be added wheredesired; thus, in forming a mortar comprising hydraulic cement, asubstance rich in monocalcium silicate, water and uncombmed oxahc anddissolved in the water component of the mixture.

FREDERICK C. LANGENBERG. HORACE S. HUNT. HERBERT G. REDDICK.

suitable for the centrifugal lining of pipes,

we have incorporated in the mortar 30 parts of sand to the 100 pounds ofcement.

We prefer, in compounding our mortar, to employ hydraulic cementscontaining a minimum quantity of soluble alkali compounds. This isparticularly the case where the mortar is to be used as a lining forwater receptacles but even where our mortar contains such soluble alkalicompounds, its marked density and impermeability to water has a markedeffect in preventing the dissolving out from the mortar of such alkalicompounds as it may embody.

While the oxalic acid which we use in compounding our mortar undoubtedlycombines with the free lime to produce an insoluble lime oxalate, itwould seem not improbable that it may also act as a catalyzer forbringing about an increased formation of dicalci um silicate in areaction between the monocalcium silicate and the lime liberated fromthe tricalcium silicate, or perhaps as a polarizer which may act to someextent in check- ,ing the reactions which bring about the formation offree lime in the mortar. It is however not important in exactly what waythe acid functions, as it undoubtedly brings about in some way thedesired condition in which the mortar is substantially free fromuncombined lime.

We have, in our copending application filed July 29, 1931, Serial Number553,895, described and claimed a method and mortar similar in allrespects to that described and claimed in the present application exceptin that we use in compounding the mortar, phosphoric acid in the placeof oxalic acid.

Having now described our invention, what we claim as new and desire tosecure by Letters Patent, is:

1. The method of compounding a hydraulic cement mortar substantiallyfree from uncombined lime which consists in mixing with the ingredientsduring the compounding of

